The common boxwood has a long history as a border and ornamental plant, particularly throughout Europe and Africa. Although the boxwood can grow as tall as 30 feet in the wild, it rarely grows that tall in cultivation. Reaching between 15 and 20 feet, this shrub has small, smooth leaves that are densely packed together, making it a perfect privacy shrub. Rated for USDA zones 6 through 9, gardeners have reported success with the shrub in zone 5. It needs full sun and alkaline soil. The shallow root system demands that the shrubs be mulched to keep the roots moist and well drained.
A favorite for the garden year after year, the fragrant lilac bush provides beautiful flowers and fragrance as well as dense foliage to make it a good privacy shrub. Flowers range from white to deep purple. Heirloom lilacs can grow as tall as 30 feet. Dwarf lilac shrubs grow as tall as 8 feet. You can plant lilacs in almost any soil, but it should be well drained and optimally have compost worked in. Too much nitrogen in the soil, however, can result in few flowers. Lilacs thrive in zones 3 through 7, making them a popular choice for those who live in northern climates.
The common privet is the shrub that most think of when they think of privacy hedges. An elegant shrub when trimmed properly, the privet is densely packed and creates a barrier unsurpassed by many other shrubs. Hardy in zones 5 through 7, the privet can reach up to 15 feet tall if left to grow. White flowers appear in spring, with a scent described as generally unpleasant. Privet will thrive in full sun to partial shade and in an alkaline soil, but it should be well drained and mulched. Some varieties tolerate more cold than others.